Updates for NGINX buildpack 1.0.0 features.
Updates for NGINX buildpack 1.0.0 features.

There are syntax changes and new templating syntax for the buildpack. This change documents those ({{port}}, {{env "variable_name"}}, and {{module "builtin_module_name"}}).
Also:
- put standard "how to push with this buildpack" section at the top
- update NGINX setup section (nginx.yml -> buildpacks.yml)

[#155953917, #156618438]

Signed-off-by: Danny Joyce <656eadb1608d5e3ea5db131e513d97abdf96b075@pivotal.io>

cloudfoundry/docs-buildpacks